<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
      body,html{
          width: 100%;
          height: 100%;
          display: flex;
          flex-direction: column;
          background-color: #c592ff;
      }
    body >{

      width: 400px;
      height: 100px;
      background-color: #c592ff;


    }
  </style>
</head>
<body>
    <input type="text" value="我是输入框">
    <input type="radio" value="男" checked="checked">
    <input type="radio" value="女" >
    <input type="checkbox" value="篮球" >

    <textarea maxlength="12" cols="4" rows="3">最大输入12个字符,三行四列</textarea>
    <!--let select=document.querySelector(".commonBound select") alert(select.value)-->
    <select >
        <option value="从我这里取值">只可以单选一个我</option>
        <option>只可以单选一个我</option>
        <optgroup label="我是label1">
            <option disabled>不可以选我</option>
            <option selected>我是默认选中</option>
        </optgroup>
        <optgroup label="我是label2">
            <option>我是</option>
            <option>我</option>
        </optgroup>
    </select>
</body>
</html>